【leetcode】Populating Next Right Pointers in Each Node II

Populating Next Right Pointers in Each Node II

Follow up for problem "Populating Next Right Pointers in Each Node".
What if the given tree could be any binary tree? Would your previous solution still work?
Note:

You may only use constant extra space.

For example,Given the following binary tree,

         1

       /  \

      2    3

     / \    \

    4   5    7

After calling your function, the tree should look like:

         1 -> NULL

       /  \

      2 -> 3 -> NULL

     / \    \

    4-> 5 -> 7 -> NULL

 
I의 사고방식과 유사하다
left->next=father->right
right->next=father->next->left;
 
단지 우리가 찾지 못했을 때,father=father->next;
우선 오른쪽 트리를 검색한 다음 왼쪽 트리를 검색해야 합니다.
 
 

 1 /**

 2  * Definition for binary tree with next pointer.

 3  * struct TreeLinkNode {

 4  *  int val;

 5  *  TreeLinkNode *left, *right, *next;

 6  *  TreeLinkNode(int x) : val(x), left(NULL), right(NULL), next(NULL) {}

 7  * };

 8  */

 9 class Solution {

10 public:

11     void connect(TreeLinkNode *root) {

12        

13         if(root==NULL)

14         {

15             return;

16         }

17        

18         if(root->left!=NULL)

19         {

20             if(root->right!=NULL)

21             {

22                 root->left->next=root->right;

23             }

24             else

25             {

26                 TreeLinkNode *tmp=root->next;

27                 root->left->next=NULL;

28                 while(tmp!=NULL)

29                 {

30                     if(tmp->left!=NULL)

31                     {

32                         root->left->next=tmp->left;

33                         break;

34                     }

35                    

36                     if(tmp->right!=NULL)

37                     {

38                         root->left->next=tmp->right;

39                         break;

40                     }

41                     tmp=tmp->next;

42                 }

43             }

44         }

45        

46         if(root->right!=NULL)

47         {

48             TreeLinkNode *tmp=root->next;

49             root->right->next=NULL;

50             while(tmp!=NULL)

51             {

52                 if(tmp->left!=NULL)

53                 {

54                     root->right->next=tmp->left;

55                     break;

56                 }

57                    

58                 if(tmp->right!=NULL)

59                 {

60                     root->right->next=tmp->right;

61                     break;

62                 }

63                 tmp=tmp->next;

64             }

65         }

66        

67        

68         connect(root->right);

69         connect(root->left);

70        

71     }

72 };